3s4x

Publication Abstract from PubMed

P99 cephalosporinase is a class C beta-lactamase that is responsible in part for the widespread bacterial resistance to beta-lactam antibiotics. Mutations of the conserved active-site residue Asn152 of the enzyme have been shown to alter beta-lactam substrate specificity in vivo. Mutation of Asn152 to a glycine is notable in that it exhibits in vivo substrate-selectivity switching. In order to better understand the structural basis for this observed switch, the X-ray crystal structure of the apo Asn152Gly mutant of P99 was determined to 1.95 A resolution. Unexpectedly, the artificial C-terminal His(6) tag of a symmetrically-related molecule was observed bound in the active site. The His(6) tag makes several interactions with key active-site residues, as well as with several sulfate ions. Additionally, the overall C-terminus occupies the space left vacant upon the mutation of Asn152 to glycine.

Structural analysis of the Asn152Gly mutant of P99 cephalosporinase.,Ruble JF, Lefurgy ST, Cornish VW, Powers RA Acta Crystallogr D Biol Crystallogr. 2012 Sep;68(Pt 9):1189-93. doi:, 10.1107/S0907444912024080. Epub 2012 Aug 18. PMID:22948919^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.